Electronic devices with non-static object detection

ABSTRACT

An electronic device may include a voltage standing wave ratio (VSWR) sensor disposed along a radio-frequency transmission line between a signal generator and an antenna. The VSWR sensor may gather VSWR measurements from radio-frequency signals transmitted by the signal generator over the transmission line. Control circuitry may identify a variation in the VSWR measurements over time and may compare the variation to a threshold value to determine whether an external object in the vicinity of the antenna is animate or inanimate. The control circuitry may reduce the maximum transmit power level of the antenna when the external object is animate and may maintain or increase the maximum transmit power level when the external object is inanimate. This may serve to maximize the wireless performance of the electronic device while also ensuring that the device complies with regulatory limits on radio-frequency energy exposure.

FIELD

This disclosure relates generally to electronic devices and, moreparticularly, to electronic devices with wireless circuitry.

BACKGROUND

Electronic devices are often provided with wireless capabilities. Anelectronic device with wireless capabilities has wireless circuitry thatincludes one or more antennas. The wireless circuitry is sometimes usedto perform spatial ranging operations in which radio-frequency signalsare used to estimate a distance between the electronic device andexternal objects.

It can be challenging to provide wireless circuitry that accuratelyestimates this distance. For example, the wireless circuitry will oftenexhibit a blind spot near the device within which the wireless circuitryis unable to accurately detect the presence of external objects. Inaddition, it can be difficult for the wireless circuitry to distinguishbetween animate and inanimate external objects.

SUMMARY

An electronic device may include wireless circuitry controlled by one ormore processors. The wireless circuitry may include an antenna coupledto a signal generator over a radio-frequency transmission line. Avoltage standing wave ratio (VSWR) sensor may be disposed along theradio-frequency transmission line. The signal generator may transmitradio-frequency signals over the radio-frequency transmission line. Theradio-frequency signals may be communications signals, radar signals, ordedicated test signals. The VSWR sensor may gather VSWR measurementsfrom the transmitted radio-frequency signals during a sampling period.

The one or more processors may identify a variation in the VSWRmeasurements gathered over the sampling period as a function of time.The one or more processors may compare the variation to a thresholdvalue to determine whether an external object in the vicinity of theantenna is animate or inanimate. The one or more processors may identifythat the external object is animate when the variation exceeds thethreshold value. The one or more processors may identify that theexternal object is inanimate when the variation is less than thethreshold value. The one or more processors may reduce a maximumtransmit power level of the antenna and may optionally identify a rangeto the external object in response to identifying that the externalobject is animate. The one or more processors may maintain or increasethe maximum transmit power level and may optionally perform removablecase detection in response to identifying that the external object isinanimate. This may serve to maximize the wireless performance of theelectronic device while also ensuring that the device complies withregulatory limits on radio-frequency energy exposure.

An aspect of the disclosure provides an electronic device operable in anenvironment that includes an external object. The electronic device caninclude an antenna. The electronic device can include a voltage standingwave ratio (VSWR) sensor communicably coupled to the antenna. The VSWRsensor can be configured to perform VSWR measurements fromradio-frequency signals transmitted by the antenna. The electronicdevice can include one or more processors. The one or more processorscan be configured to identify a variation in the VSWR measurements overtime. The one or more processors can be configured to determine whetherthe external object is animate or inanimate based on the identifiedvariation in the VSWR measurements.

An aspect of the disclosure provides a method of operating an electronicdevice to perform animate object detection on an object external to theelectronic device. The method can include with a signal generator,transmitting radio-frequency signals during a sampling period over aradio-frequency transmission line communicably coupled to an antenna.The method can include with a voltage standing wave ratio (VSWR) sensordisposed along the radio-frequency transmission line, performing VSWRmeasurements from the radio-frequency signals transmitted over theradio-frequency transmission line during the sampling period. The methodcan include with one or more processors, identifying a variation in theVSWR measurements as a function of time within the sampling period. Themethod can include with the one or more processors, identifying that theobject is animate when the identified variation exceeds a thresholdvalue. The method can include with the one or more processors,identifying that the object is inanimate when the identified variationis less than the threshold value.

An aspect of the disclosure provides an electronic device. Theelectronic device can include an antenna. The electronic device caninclude a voltage standing wave ratio (VSWR) sensor communicably coupledto the antenna. The VSWR sensor can be configured to measure VSWR valuesfrom radio-frequency signals transmitted by the antenna. The electronicdevice can include one or more processors. The one or more processorscan be configured to identify a variation in the VSWR values over time.The one or more processors can be configured to decrease a maximumtransmit power level of the antenna when the identified variationexceeds a threshold value. The one or more processors can be configuredto maintain or increase the maximum transmit power level of the antennawhen the identified variation is less than the threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of an illustrative electronicdevice having a transmit antenna that is used to perform animateexternal object detection in accordance with some embodiments.

FIG. 2 is a plot of reflection coefficient as a function of frequencythat may be produced by an illustrative voltage standing wave ratio(VSWR) sensor in response to the absence and presence of an externalobject adjacent to a transmit antenna in accordance with someembodiments.

FIG. 3 is a circuit diagram of an illustrative VSWR sensor having adirectional coupler for performing animate external object detectionusing a transmit antenna in accordance with some embodiments.

FIG. 4 is a plot showing how the reflection coefficient measured by anillustrative VSWR sensor may vary at different times when an animateobject is present adjacent to a transmit antenna in accordance with someembodiments.

FIG. 5 is a plot showing how the reflection coefficient measured by anillustrative VSWR sensor may vary as a function of time in the presenceof an inanimate external object, in the presence of an animate externalobject, and in the presence of no external object adjacent to a transmitantenna in accordance with some embodiments.

FIG. 6 is a plot showing how the return loss measured by an illustrativeVSWR sensor may vary when the electronic device is provided withdifferent types of removable cases in accordance with some embodiments.

FIG. 7 is a flow chart of illustrative operations involved in gatheringVSWR measurements with a VSWR sensor for use in performing animateobject detection in accordance with some embodiments.

FIG. 8 is a flow chart of illustrative operations involved in performinganimate object detection based on variations in VSWR measurementsgathered by a VSWR sensor in accordance with some embodiments.

FIG. 9 is a plot showing how reflection coefficient variation may becorrelated to the range between a transmit antenna and an externalobject in accordance with some embodiments.

FIG. 10 shows illustrative timing diagrams for gathering VSWRmeasurements using a VSWR sensor for performing animate object detectionin accordance with some embodiments.

DETAILED DESCRIPTION

Electronic device 10 of FIG. 1 may be a computing device such as alaptop computer, a desktop computer, a computer monitor containing anembedded computer, a tablet computer, a cellular telephone, a mediaplayer, or other handheld or portable electronic device, a smallerdevice such as a wristwatch device, a pendant device, a headphone orearpiece device, a device embedded in eyeglasses or other equipment wornon a user's head, or other wearable or miniature device, a television, acomputer display that does not contain an embedded computer, a gamingdevice, a navigation device, an embedded system such as a system inwhich electronic equipment with a display is mounted in a kiosk orautomobile, a wireless internet-connected voice-controlled speaker, ahome entertainment device, a remote control device, a gaming controller,a peripheral user input device, a wireless base station or access point,equipment that implements the functionality of two or more of thesedevices, or other electronic equipment.

As shown in the functional block diagram of FIG. 1 , device 10 mayinclude components located on or within an electronic device housingsuch as housing 12. Housing 12, which may sometimes be referred to as acase, may be formed of plastic, glass, ceramics, fiber composites, metal(e.g., stainless steel, aluminum, metal alloys, etc.), other suitablematerials, or a combination of these materials. In some situations,parts or all of housing 12 may be formed from dielectric or otherlow-conductivity material (e.g., glass, ceramic, plastic, sapphire,etc.). In other situations, housing 12 or at least some of thestructures that make up housing 12 may be formed from metal elements.

Device 10 may include control circuitry 14. Control circuitry 14 mayinclude storage such as storage circuitry 16. Storage circuitry 16 mayinclude hard disk drive storage, nonvolatile memory (e.g., flash memoryor other electrically-programmable-read-only memory configured to form asolid-state drive), volatile memory (e.g., static or dynamicrandom-access-memory), etc. Storage circuitry 16 may include storagethat is integrated within device 10 and/or removable storage media.

Control circuitry 14 may include processing circuitry such as processingcircuitry 18. Processing circuitry 18 may be used to control theoperation of device 10. Processing circuitry 18 may include on one ormore microprocessors, microcontrollers, digital signal processors, hostprocessors, baseband processor integrated circuits, application specificintegrated circuits, central processing units (CPUs), etc. Controlcircuitry 14 may be configured to perform operations in device 10 usinghardware (e.g., dedicated hardware or circuitry), firmware, and/orsoftware. Software code for performing operations in device 10 may bestored on storage circuitry 16 (e.g., storage circuitry 16 may includenon-transitory (tangible) computer readable storage media that storesthe software code). The software code may sometimes be referred to asprogram instructions, software, data, instructions, or code. Softwarecode stored on storage circuitry 16 may be executed by processingcircuitry 18.

Control circuitry 14 may be used to run software on device 10 such assatellite navigation applications, internet browsing applications,voice-over-internet-protocol (VOIP) telephone call applications, emailapplications, media playback applications, operating system functions,etc. To support interactions with external equipment, control circuitry14 may be used in implementing communications protocols. Communicationsprotocols that may be implemented using control circuitry 14 includeinternet protocols, wireless local area network (WLAN) protocols (e.g.,IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols forother short-range wireless communications links such as the Bluetooth®protocol or other wireless personal area network (WPAN) protocols, IEEE802.11ad protocols (e.g., ultra-wideband protocols), cellular telephoneprotocols (e.g., 3G protocols, 4G (LTE) protocols, 5G protocols, etc.),antenna diversity protocols, satellite navigation system protocols(e.g., global positioning system (GPS) protocols, global navigationsatellite system (GLONASS) protocols, etc.), antenna-based spatialranging protocols (e.g., radio detection and ranging (RADAR) protocolsor other desired range detection protocols for signals conveyed atmillimeter and centimeter wave frequencies), or any other desiredcommunications protocols. Each communications protocol may be associatedwith a corresponding radio access technology (RAT) that specifies thephysical connection methodology used in implementing the protocol.

Device 10 may include input-output circuitry 20. Input-output circuitry20 may include input-output devices 22. Input-output devices 22 may beused to allow data to be supplied to device 10 and to allow data to beprovided from device 10 to external devices. Input-output devices 22 mayinclude user interface devices, data port devices, and otherinput-output components. For example, input-output devices 22 mayinclude touch sensors, displays (e.g., touch-sensitive and/orforce-sensitive displays), light-emitting components such as displayswithout touch sensor capabilities, buttons (mechanical, capacitive,optical, etc.), scrolling wheels, touch pads, key pads, keyboards,microphones, cameras, buttons, speakers, status indicators, audio jacksand other audio port components, digital data port devices, motionsensors (accelerometers, gyroscopes, and/or compasses that detectmotion), capacitance sensors, temperature sensors, proximity sensors,magnetic sensors, force sensors (e.g., force sensors coupled to adisplay to detect pressure applied to the display), etc. In someconfigurations, keyboards, headphones, displays, pointing devices suchas trackpads, mice, and joysticks, and other input-output devices may becoupled to device 10 using wired or wireless connections (e.g., some ofinput-output devices 22 may be peripherals that are coupled to a mainprocessing unit or other portion of device 10 via a wired or wirelesslink).

Input-output circuitry 20 may include wireless circuitry 24 to supportwireless communications and/or radio-based spatial ranging operations.Wireless circuitry 24 may include two or more antennas 40. Wirelesscircuitry 24 may also include baseband processor circuitry, transceivercircuitry, amplifier circuitry, filter circuitry, switching circuitry,analog-to-digital converter (ADC) circuitry, digital-to-analog converter(DAC) circuitry, radio-frequency transmission lines, and/or any othercircuitry for transmitting and/or receiving radio-frequency signalsusing antennas 40.

Antennas 40 may be formed using any desired antenna structures. Forexample, antennas 40 may include antennas with resonating elements thatare formed from loop antenna structures, patch antenna structures,inverted-F antenna structures, slot antenna structures, planarinverted-F antenna structures, helical antenna structures, monopoleantennas, dipoles, hybrids of these designs, etc. Filter circuitry,switching circuitry, impedance matching circuitry, and/or other antennatuning components may be adjusted to adjust the frequency response andwireless performance of antennas 40 over time.

Antennas 40 may include one or more transmit (TX) antennas such astransmit antenna 40TX and one or more receive (RX) antennas such asreceive antenna 40RX. Antennas 40 may include zero, one, or more thanone additional antenna used in the transmission and/or reception ofradio-frequency signals. Transmit antenna 40TX may transmitradio-frequency signals such as radio-frequency signals 42 and/orradio-frequency signals 38. Receive antenna 40RX may receiveradio-frequency signals such as radio-frequency signals 44 and/orradio-frequency signals 38. Wireless circuitry 24 may use antennas 40 totransmit and/or receive radio-frequency signals 38 to convey wirelesscommunications data between device 10 and external wirelesscommunications equipment 48 (e.g., one or more other devices such asdevice 10, a wireless access point or base station, etc.). Wirelesscommunications data may be conveyed by wireless circuitry 24bidirectionally or unidirectionally. The wireless communications datamay, for example, include data that has been encoded into correspondingdata packets such as wireless data associated with a telephone call,streaming media content, internet browsing, wireless data associatedwith software applications running on device 10, email messages, etc.

Wireless circuitry 24 may include communications circuitry 26 (sometimesreferred to herein as wireless communications circuitry 26) fortransmitting and/or receiving wireless communications data usingantennas 40. Communications circuitry 26 may include baseband circuitry(e.g., one or more baseband processors) and one or more radios (e.g.,radio-frequency transceivers, modems, etc.) for conveyingradio-frequency signals 38 using one or more antennas 40 (e.g., transmitantenna 40TX, receive antenna 40RX, and/or other antennas 40).

Communications circuitry 26 may transmit and/or receive radio-frequencysignals 38 within a corresponding frequency band at radio frequencies(sometimes referred to herein as a communications band or simply as a“band”). The frequency bands handled by communications circuitry 26 mayinclude wireless local area network (WLAN) frequency bands (e.g., Wi-Fi®(IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLANband (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or otherWi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network(WPAN) frequency bands such as the 2.4 GHz Bluetooth® band or other WPANcommunications bands, cellular telephone frequency bands (e.g., bandsfrom about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New RadioFrequency Range 1 (FR1) bands below 10 GHz, 5G New Radio Frequency Range2 (FR2) bands between 20 and 60 GHz, etc.), other centimeter ormillimeter wave frequency bands between 10-300 GHz, near-fieldcommunications frequency bands (e.g., at 13.56 MHz), satellitenavigation frequency bands (e.g., a GPS band from 1565 to 1610 MHz, aGlobal Navigation Satellite System (GLONASS) band, a BeiDou NavigationSatellite System (BDS) band, etc.), ultra-wideband (UWB) frequency bandsthat operate under the IEEE 802.15.4 protocol and/or otherultra-wideband communications protocols, communications bands under thefamily of 3GPP wireless communications standards, communications bandsunder the IEEE 802.XX family of standards, and/or any other desiredfrequency bands of interest.

Communications circuitry 26 may be coupled to antennas 40 using one ormore transmit paths and/or one or more receive paths. Communicationscircuitry 26 uses the transmit paths to transmit radio-frequency signals38 and uses the receive paths to receive radio-frequency signals 38. Ifdesired, communications circuitry 26 may be coupled to transmit antenna40TX over a transmit path such as transmit path 34. Communicationscircuitry 26 may use transmit path 34 to transmit radio-frequencysignals 38 using transmit antenna 40TX. Transmit path 34 (sometimesreferred to herein as transmit chain 34) may include one or more signalpaths (e.g., radio-frequency transmission lines), amplifier circuitry,filter circuitry, switching circuitry, radio-frequency front endcircuitry (e.g., components on a radio-frequency front end module),and/or any other desired paths or circuitry for transmittingradio-frequency signals from communications circuitry 26 to transmitantenna 40TX.

In addition to conveying wireless communications data, wirelesscircuitry 24 may also use antennas 40 to perform spatial rangingoperations. Wireless circuitry 24 may include long range spatial rangingcircuitry 28 for performing spatial ranging operations. Long rangespatial ranging circuitry 28 may include mixer circuitry, amplifiercircuitry, transmitter circuitry (e.g., signal generators, synthesizers,etc.), receiver circuitry, filter circuitry, baseband circuitry, ADCcircuitry, DAC circuitry, and/or any other desired components used inperforming spatial ranging operations using antennas 40. Long rangespatial ranging circuitry 28 may include, for example, radar circuitry(e.g., frequency modulated continuous wave (FMCW) radar circuitry, OFDMradar circuitry, FSCW radar circuitry, a phase coded radar circuitry,other types of radar circuitry). Antennas 40 may include separateantennas for conveying wireless communications data and radio-frequencysignals for spatial ranging or may include one or more antennas 40 thatare used to both convey wireless communications data and to performspatial ranging. Using a single antenna 40 to both convey wirelesscommunications data and perform spatial ranging may, for example, serveto minimize the amount of space occupied in device 10 by antennas 40.

In one embodiment that is described herein as an example, wirelesscircuitry 24 may use transmit antenna 40TX to both convey wirelesscommunications data for communications circuitry 26 and perform spatialranging operations for long ranging spatial ranging circuitry 28. Longrange spatial ranging circuitry 28 may therefore be coupled to transmitantenna 40TX over transmit path 34. When performing spatial rangingoperations, long range spatial ranging circuitry 28 may use transmitantenna 40TX to transmit radio-frequency signals 42. Radio-frequencysignals 42 may include one or more signal tones, continuous waves ofradio-frequency energy, wideband signals, chirp signals, or any otherdesired transmit signals (e.g., radar signals) for use in spatialranging operations. Unlike radio-frequency signals 38, radio-frequencysignals 42 may be free from wireless communications data (e.g., cellularcommunications data packets, WLAN communications data packets, etc.).Radio-frequency signals 42 may sometimes also be referred to herein asspatial ranging signals 42, long range spatial ranging signals 42, orradar signals 42. Long range spatial ranging circuitry 28 may transmitradio-frequency signals 42 at one or more carrier frequencies in acorresponding radio frequency band such (e.g., a frequency band thatincludes frequencies greater than around 10 GHz, greater than around 20GHz, less than 10 GHz, 20-30 GHz, greater than 40 GHz, etc.).

Radio-frequency signals 42 may reflect off of objects external to device10 such as external object 46. External object 46 may be, for example,the ground, a building, part of a building, a wall, furniture, aceiling, a person, a body part, an animal, a vehicle, a landscape orgeographic feature, an obstacle, external communications equipment suchas external wireless communications equipment 48, another device of thesame type as device 10 or a peripheral device such as a gamingcontroller or remote control, or any other physical object or entitythat is external to device 10. Receive antenna 40RX may receivereflected radio-frequency signals 44. Reflected signals 44 may be areflected version of the transmitted radio-frequency signals 42 thathave reflected off of external object 46 and back towards device 10.

Receive antenna 40RX may be coupled to long range spatial rangingcircuitry 28 over receive path 36 (sometimes referred to herein asreceive chain 36). Long range spatial ranging circuitry 28 may receivereflected signals 44 from receive antenna 40RX via receive path 36.Receive path 36 may include one or more signal paths (e.g.,radio-frequency transmission lines), amplifier circuitry (e.g., lownoise amplifier (LNA) circuitry), filter circuitry, switching circuitry,radio-frequency front end circuitry (e.g., components on aradio-frequency front end module), and/or any other desired paths orcircuitry for conveying radio-frequency signals from receive antenna40RX to long range spatial ranging circuitry 28.

Control circuitry 14 may process the transmitted radio-frequency signals42 and the received reflected signals 44 to detect or estimate the rangeR between device 10 and external object 46. If desired, controlcircuitry 14 may also process the transmitted and received signals toidentify a two or three-dimensional spatial location (position) ofexternal object 46, a velocity of external object 46, and/or an angle ofarrival of reflected signals 44. If desired, a loopback path such asloopback path 50 may be coupled between transmit path 34 and receivepath 36. Loopback path 50 may be used to convey transmit signals ontransmit path 34 to receiver circuitry in long range spatial rangingcircuitry 28. As an example, in embodiments where long range spatialranging circuitry 28 performs spatial ranging using an FMCW scheme,loopback path 50 may be a de-chirp path that conveys chirp signals ontransmit path 34 to a de-chirp mixer in long range spatial rangingcircuitry 28. In these embodiments, doppler shifts in continuous wavetransmit signals may be detected and processed to identify the velocityof external object 46, and the time dependent frequency differencebetween radio-frequency signals 42 and reflected signals 44 may bedetected and processed to identify range R and/or the position ofexternal object 46. Use of continuous wave signals for estimating rangeR may allow control circuitry 14 to reliably distinguish betweenexternal object 46 and other background or slower-moving objects, forexample. This example is merely illustrative and, in general, long rangespatial ranging circuitry 28 may implement any desired radar or longrange spatial ranging scheme.

The radio-frequency transmission lines in transmit path 34 and receivepath 36 may include coaxial cables, microstrip transmission lines,stripline transmission lines, edge-coupled microstrip transmissionlines, edge-coupled stripline transmission lines, transmission linesformed from combinations of transmission lines of these types, etc.Transmission lines in device may be integrated into rigid and/orflexible printed circuit boards if desired. One or more radio-frequencylines may be shared between transmit path 34 and receive path 36 ifdesired. The components of wireless circuitry 24 may be formed on one ormore common substrates or modules (e.g., rigid printed circuit boards,flexible printed circuit boards, integrated circuits, chips, packages,systems-on-chip, etc.).

The example of FIG. 1 is merely illustrative. While control circuitry 14is shown separately from wireless circuitry 24 in the example of FIG. 1for the sake of clarity, wireless circuitry 24 may include processingcircuitry that forms a part of processing circuitry 18 and/or storagecircuitry that forms a part of storage circuitry 16 of control circuitry14 (e.g., portions of control circuitry 14 may be implemented onwireless circuitry 24). As an example, some or all of the basebandcircuitry in wireless circuitry 24 may form a part of control circuitry14. In addition, wireless circuitry 24 may include any desired number ofantennas 40. Antennas 40 may include more than one transmit antenna40TX, more than one receive antenna 40RX, and zero, one, or more thanone other antenna 40. Each antenna 40 may be coupled to communicationscircuitry 26 and/or long range spatial ranging circuitry 28 overdedicated transmit and/or receive paths or over one or more transmitand/or receive paths that are shared between antennas.

Long range spatial ranging circuitry 28 need not be coupled to all ofthe antennas 40 in wireless circuitry 24. Similarly, communicationscircuitry 26 need not be coupled to all of the antennas 40 in wirelesscircuitry 24 (e.g., some antennas 40 may be used to only perform spatialranging operations without conveying wireless communications data or toonly convey wireless communications data without performing spatialranging). Antennas 40 that are only used to receive signals may becoupled to communications circuitry 26 and/or long range spatial rangingcircuitry 28 using one or more receive paths (e.g., receive path 36).Antennas 40 that are only used to transmit signals may be coupled tocommunications circuitry 26 and/or long range spatial ranging circuitry28 using one or more transmit paths (e.g., transmit path 34). One ormore antennas 40 may be used to both transmit and receive signals. Inthese scenarios, the antenna may be coupled to communications circuitry26 and/or long range spatial ranging circuitry 28 using both a transmitpath and a receive path and, if desired, one or more components orsignal paths (e.g., radio-frequency transmission lines) may be sharedbetween both the transmit path and the receive path. While describedherein as a transmit antenna for the sake of simplicity, transmitantenna 40TX may also be used in the reception of radio-frequencysignals for communications circuitry 26 if desired (e.g., an additionalreceive path (not shown) may couple transmit antenna 40TX tocommunications circuitry 26). Similarly, receive antenna 40RX may alsobe used in the transmission of radio-frequency signals if desired. Whilereceive antenna 40RX is only illustrated as providing reflected signals44 to long range spatial ranging circuitry 28, receive antenna 40RX mayalso provide received radio-frequency signals 38 to communicationscircuitry 26 (e.g., receive path 36 may also couple receive antenna 40RXto communications circuitry 26).

Long range spatial ranging circuitry 28 may be used to accuratelyidentify range R when external object 46 is at relatively far distancesfrom device 10. However, in practice, long range spatial rangingcircuitry 28 exhibits a blind spot to nearby external objects atdistances less than threshold range R_(TH) (e.g., around 1-2 cm) fromdevice 10. When external object 46 is located within this blind spot(e.g., within threshold range R_(TH) from transmit antenna 40TX), longrange spatial ranging circuitry 28 may be unable to identify thepresence, location, and/or velocity of external object 46 with asatisfactory level of accuracy. External objects 46 within thresholdrange R_(TH) of transmit antenna 40TX may be exposed to relatively highamounts of radio-frequency energy (e.g., from the radio-frequencysignals 38 and/or 42 that are transmitted by transmit antenna 40TX). Inscenarios where external object 46 is a body part or person, if care isnot taken, this transmitted radio-frequency energy may cause wirelesscircuitry 24 to exceed regulatory limits or other limits on specificabsorption rate (SAR) (e.g., when the transmitted signals are atfrequencies below 6 GHz) and/or maximum permissible exposure (MPE)(e.g., when the transmitted signals are at frequencies above 6 GHz). Inorder to detect the presence of external object 46 within thresholdrange R_(TH) from transmit antenna 40TX, wireless circuitry 24 mayinclude an ultra-short range (USR) object detector such as USR detector30. USR detector 30 may serve to detect external object 46 atultra-short ranges (e.g., at ranges within threshold range R_(TH) fromtransmit antenna 40TX). In other words, USR detector 30 may performexternal object detection within the blind spot of long range spatialranging circuitry 28.

USR detector 30 may include a voltage standing wave ratio (VSWR) sensor(detector) such as VSWR sensor 32. VSWR sensor 32 may be interposed ontransmit path 34. VSWR sensor 32 may gather VSWR values using transmitantenna 40TX. The VSWR values may include complex scattering parametervalues (S-parameter values) such as reflection coefficient (return loss)values (e.g., S₁₁ values). The magnitude of the S₁₁ values (e.g., |S₁₁|values) may be indicative of the amount of transmitted radio-frequencyenergy that is reflected in a reverse direction along transmit path 34(e.g., in response to the presence of external object 46 at or adjacentto transmit antenna 40TX). The VSWR values gathered by VSWR sensor 32may be insensitive to situations where external object 46 is located atdistances greater than threshold range R_(TH) from transmit antenna40TX. However, the VSWR values gathered by VSWR sensor 32 may allowcontrol circuitry 14 to identify when external object 46 is locatedwithin threshold range R_(TH) from transmit antenna 40TX (e.g., withinthe blind spot of long range spatial ranging circuitry 28).

In this way, USR detector 30 and long range spatial ranging circuitry 28may identify the presence of external object 46 and optionally the rangeR to external object 46, regardless of whether external object 46 hasmoved to a position that is relatively close or relatively far fromdevice 10 over time. In addition, USR detector 30 may identify thepresence of external object 46 within the blind spot of long rangespatial ranging circuitry 28 so that suitable action can be taken toensure that wireless circuitry 24 continues to satisfy any applicableSAR and/or MPE regulations. By using the same transmit antenna 40TX toboth transmit radio-frequency signals 38/42 and measure VSWR, the VSWRmeasurements will be very closely correlated with the amount ofradio-frequency energy absorbed by external object 46 from thetransmitted radio-frequency signals 38/42, thereby providing highconfidence in the use of USR detector 30 for meeting any applicable SARand/or MPE regulations (e.g., greater confidence than in scenarios whereproximity sensors that are separate from the transmit antenna ortransmit chain are used to identify the presence of external objectswithin threshold range R_(TH) of device 10).

FIG. 2 is a plot showing how VSWR measurements made by VSWR sensor 32may change due to the presence of external object 46 adjacent totransmit antenna 40TX. Curve 60 plots the magnitude of reflectionS-parameter S₁₁ (i.e., |S₁₁|) as a function of frequency in the absenceof external object 46 within threshold range R_(TH). As shown by curve60, in the absence of external object 46, |S₁₁| may have a relativelyhigh value across a frequency band of interest B (e.g., the frequencyband used to convey radio-frequency signals 38 or 42 of FIG. 1 ).

Curve 62 plots |S₁₁| as a function of frequency when external object 46is within threshold range R_(TH) from transmit antenna 40TX. As shown bycurve 62, |S₁₁| may have a relatively low value across frequency band Bdue to the presence of external object 46. In general, once externalobject 46 is within threshold range R_(TH), |S₁₁| will continue todecrease, as shown by arrow 64 as the object approaches transmit antenna40TX. Control circuitry 14 may gather VSWR values using VSWR sensor 32(e.g., |S₁₁| values such as those shown by curves 60 and 62) and mayprocess the gathered VSWR values to identify when external object 46 iswithin threshold range R_(TH) (e.g., by comparing the gathered Billvalues to one or more threshold levels). Beyond threshold range R_(TH),|S₁₁| will exhibit no change or a negligible change in response tochanges in distance between transmit antenna 40TX and external object46. At these relatively far distances, long range spatial rangingcircuitry 28 (FIG. 1 ) may be used to detect the presence, position(e.g., range R), and/or velocity of external object 46.

FIG. 3 is a circuit diagram showing how VSWR sensor 32 may be disposedon transmit path 34. As shown in FIG. 3 , transmit path 34 may include apower amplifier (PA) such as PA 96. The input of PA 96 may be coupled tolong range spatial ranging circuitry 28 and/or communications circuitry26 of FIG. 1 . The output of PA 96 may be coupled to transmit antenna40TX via a switch such as antenna switch 94. The output of PA 96 mayalso be coupled to matched load 88 via a switch such as matched loadswitch 90. Matched load 88 may be coupled in series between matched loadswitch 90 and ground 82. Matched load 88, matched load switch 90, and/orantenna switch 94 may be omitted if desired.

In the example of FIG. 3 , VSWR sensor 32 is a directional switchcoupler. This is merely illustrative and, in general, VSWR sensor 32 maybe implemented using any desired VSWR sensor architecture. As shown inFIG. 3 , VSWR sensor 32 may include directional coupler 72 interposed ontransmit path 34 between PA 96 and transmit antenna 40TX (e.g., along aradio-frequency transmission line in transmit path 34 coupled betweenthe output of PA 96 and transmit antenna 40TX). Directional coupler 72may have a first port (P1) coupled to the output of PA 96 and a secondport (P2) communicably coupled to transmit antenna 40TX. Directionalcoupler 72 may have a third port (P3) coupled to a first terminationthat includes resistor 84 coupled in series between termination switch78 and ground 82. Directional coupler 72 may also have a fourth port(P4) coupled to a second termination that includes resistor 86 coupledin series between termination switch 80 and ground 82. VSWR sensor 32may have a forward (FW) switch 74 coupled between port P3 andmeasurement circuitry 70 (e.g., an amplitude and/or phase detector).VSWR sensor 32 may also have a reverse (RW) switch 76 coupled betweenport P4 and measurement circuitry 70.

Measurement circuitry 70 may have a control path coupled to othercomponents in USR detector 30 or control circuitry 14 (FIG. 1 ) and/orsome or all of measurement circuitry 70 may form a part of controlcircuitry 14 (e.g., the operations of some or all of measurementcircuitry 70 may be performed using one or more processors). Measurementcircuitry 70 may include, for example, a power detector such as powerdetector 98, an in-phase and quadrature-phase (I/Q) detector (e.g., anADC), logic such as comparator/logic 102 (e.g., one or more logic gates,etc.), and/or memory such as memory 104. Memory 104 may form a part ofstorage circuitry 16 of FIG. 1 , for example. If desired, I/Q detector100 may be formed from one or more ADCs in receive path 36 (FIG. 1 ).

When performing VSWR measurements (e.g., S-parameter values such as Srivalues), PA 96 may output a transmit test signal sigtx (e.g., whileantenna switch 94 is closed). Test signal sigtx may be a radar transmitsignal transmitted by long range spatial ranging circuitry 28 (e.g.,radio-frequency signals 42 of FIG. 1 ), a wireless communications datatransmit signal transmitted by communications circuitry 26 (e.g.,radio-frequency signals 38 of FIG. 1 ), or a dedicated test signal foruse in VSWR measurement (e.g., one or more tones transmitted by a signalgenerator, local oscillator, and/or other signal generation circuitry inUSR detector 30 of FIG. 1 ). For example, a sequential signal generator108 may be used to generate test signal sigtx. Sequential signalgenerator 108 may be a part of long range spatial ranging circuitry 28(e.g., test signal sigtx may be a continuous wave or wideband that canalso be used in performing long range spatial ranging operations), maybe a part of communications circuitry 26 (e.g., test signal sigtx mayalso carry wireless communications data), or may be formed as a part ofUSR detector 30 that is separate from long range spatial rangingcircuitry 28 and communications circuitry 26. Additionally oralternatively, a simple local oscillator such as local oscillator (LO)106 may generate test signal sigtx.

In performing VSWR measurements, VSWR sensor 32 may perform forward pathmeasurements and reverse path measurements using transmit signal sigtx.When performing forward path measurements, FW switch 74 is closed, RWswitch 76 is open, switch 80 is closed, and switch 78 is open so thattest signal sigtx is coupled off from transmit path 34 by directionalcoupler 72 and routed to measurement circuitry 70 through FW switch 74.Measurement circuitry 70 may measure and store the amplitude (magnitude)and/or phase of test signal sigtx for further processing (e.g., as aforward signal phase and magnitude measurement). For example, powerdetector 98 (e.g., a peak detector, diode and capacitor, etc.) maymeasure the magnitude of test signal sigtx and may store the magnitudeon memory 104. As another example, I/Q detector 100 may make I/Qmeasurements for the forward path that are stored on memory 104.

At least some of test signal sigtx will reflect off of transmit antenna40TX (e.g., due to impedance discontinuities between transmit path 34and transmit antenna 40TX subject to impedance loading from any externalobjects at or adjacent to transmit antenna 40TX) and back towards PA 96as reflected test signal sigtx′. When performing reverse pathmeasurements, FW switch 74 is open, RW switch 76 is closed, switch 80 isopen, and switch 78 is closed so that reflected test signal sigtx′ iscoupled off of transmit path 34 by directional coupler 72 and routed tomeasurement circuitry 70 through RW switch 76. Measurement circuitry 70(e.g., power detector 98 or I/Q detector 100) may measure and store theamplitude (magnitude) and/or phase of reflected test signal sigtx′ forfurther processing (e.g., as a reverse signal phase and magnitudemeasurement). Comparator/logic 102 and/or control circuitry 14 (FIG. 1 )may process the stored forward and reverse phase and magnitudemeasurements to identify complex scattering parameter values such as S₁₁values. The S₁₁ values are characterized by a scalar magnitude |S₁₁| anda corresponding phase. In this way, VSWR sensor 32 may measure VSWRvalues (e.g., S₁₁ values, |S₁₁| values, etc.) that can be used todetermine when external object 46 is located at a range R that is lessthan or equal to threshold range R_(TH). Long range spatial rangingcircuitry 28 (FIG. 1 ) may also use transmit antenna 40TX to identifyrange R when external object 46 is located at a range R that is beyondthreshold range R_(TH) from transmit antenna 40TX.

It may be desirable for USR detector 30 to be able to distinguishbetween animate external objects 46 and inanimate external objects 46 inthe vicinity of transmit antenna 40TX (e.g., within threshold rangeR_(TH) from transmit antenna 40TX). For example, inanimate objects maynot be subject to regulatory limits on SAR or MPE, whereas animateobjects are likely to be human body parts that are subject to regulatorylimits on SAR or MPE. If USR detector 30 is able to detect that anexternal object 46 present within threshold range R_(TH) of transmitantenna 40TX is an inanimate object, wireless circuitry 24 may be ableto continue to transmit signals over transmit antenna 40TX at relativelyhigh transmit power levels (e.g., the maximum transmit power level of PA96) without violating regulatory limits on SAR or MPE. This may serve tomaximize the wireless performance of device 10 in performing wirelesscommunications and/or long range spatial ranging operations relative toscenarios where the wireless circuitry has to reduce transmit powerlevel or maximum transmit power level in the presence of any externalobject within threshold range R_(TH) regardless of whether the externalobject is animate or inanimate. At the same time, if USR detector 30 isable to detect that an external object 46 present within threshold rangeR_(TH) of transmit antenna 40TX is an animate object, wireless circuitry24 may have relatively high confidence that the external object is abody part subject to SAR/MPE limits and may therefore reduce thetransmit power level or the maximum transmit power level for transmitantenna 40TX to ensure that regulatory limits on SAR or MPE aresatisfied.

If desired, control circuitry 14 (FIG. 1 ) may use variations in theVSWR measurements performed by VSWR sensor 32 over time to determinewhether an external object 46 adjacent to transmit antenna 40TX isanimate or inanimate. FIG. 4 is a plot showing how VSWR measurements(e.g., |S₁₁| values) performed by VSWR sensor 32 may vary over time inthe presence of an external object adjacent to transmit antenna 40TX.

Curve C1 of FIG. 4 illustrates |S₁₁| values that may be generated bymeasurement circuitry 70 (FIG. 3 ) at different frequencies and at afirst time (e.g., in response to test signals sigtx that are swept overa range of frequencies). Curve C2 illustrates |S₁₁| values that may begenerated by measurement circuitry 70 at different frequencies and at asecond time. As shown by curves C1 and C2, the |S₁₁| measurementsgathered by measurement circuitry 70 may vary at a given frequency F bydifference (variation) 110 between the first and second times. Ingeneral, animate objects will produce more variation in the |S₁₁|measurements at a given frequency over time than inanimate objects.Control circuitry 14 may therefore gather a sufficient number of VSWRmeasurements over time, may process the VSWR measurements to identifydifferences (variations) in the VSWR measurements over time (e.g.,differences such as difference 110 of FIG. 4 ), and may process theidentified differences to determine whether external object 46 isinanimate or animate. The example of FIG. 4 is merely illustrative and,in practice, curves C1 and C2 may have other shapes.

Some examples of inanimate objects 46 that may be present adjacent totransmit antenna 40TX include furniture, tabletops, desktops, vehicledashboards, or removable device cases (e.g., removable plastic cases,rubber cases, leather cases, cases with a combination of materials,etc.) for device 10. If desired, control circuitry 14 may also use theidentified differences (variations) in VSWR measurements over time todetermine whether device 10 has been placed within a removeable case(e.g., to determine whether external object 46 is a removable case fordevice 10). Since different users will place device 10 into differenttypes of removable cases having different dielectric properties, controlcircuitry 14 may further determine what type of removable case ispresent and/or the effects of the removable case for calibrating otherdevice operations if desired. For example, control circuitry 14 may usethe presence of the removable case and/or information about the type ofremovable case that is present to calibrate subsequent radar operationsperformed by long range spatial ranging circuitry 28 (e.g., to adjustestimates of range R to account for the path loss effects of thetransmitted and received signals which have to pass through theremovable case), to adjust the impedance matching and/or tuning oftransmit antenna 40TX (e.g., to compensate for dielectric loading by theremovable case to minimize signal reflections at the transmit antennaand so that the transmit antenna is not undesirably detuned away fromits desired operating frequency), to adjust future VSWR measurements,etc.

FIG. 5 is a plot of different reflection coefficient (return loss)magnitude measurements (|S₁₁| values) that may be made by VSWR sensor 32as a function of time in the presence of different types of externalobjects 46. Points 114 of FIG. 5 illustrate |S₁₁| measurements made byVSWR sensor 32 in the absence of any external objects (e.g., at fivedifferent sampling times such as times T0, T1, T2, T3, and T4). Points114 may, for example, be predetermined points that are generated duringfactory calibration of device 10. As shown by points 114, there isrelatively little variation in |S₁₁| (e.g., no variation) as a functionof time in the absence of external objects.

Points 112 illustrate |S₁₁| measurements that may be made by VSWR sensor32 at times T0-T4 in the presence of an inanimate object adjacent totransmit antenna 40TX. The inanimate object may be, for example, aremovable case for device 10. As shown by points 112, there isrelatively little variation in |S₁₁| as a function of time in thepresence of an inanimate object such as a removable device case. Controlcircuitry 14 may compare points 112 to predetermined points 114 todetermine that an inanimate object such as a removable device case ispresent. If desired, control circuitry 14 may compare points 114 toother predetermined points that are known to be associated withdifferent types of removable device cases (e.g., predetermined pointsstored on device 10 during factory calibration in the presence of thedifferent types of removable cases) to identify the type of removabledevice case that is present.

Points 116 illustrate |S₁₁| measurements that may be made by VSWR sensor32 at times T0-T4 in the presence of an animate object adjacent totransmit antenna 40TX. The animate object may be, for example, a bodypart. As shown by points 116, there is a relatively high amount ofvariation in |S₁₁| as a function of time in the presence of an animateobject such as a body part (e.g., due to minute movements of theexternal object relative to static/inanimate objects such as a removabledevice case). Control circuitry 14 may perform animate object detectionby performing |S₁₁| measurements at different times (e.g., times T0-T4)to produce points such as points 114, 112, or 116 of FIG. 5 . Controlcircuitry 14 may identify variations in the |S₁₁| measurements over timeto determine whether an external object adjacent to transmit antenna40TX is an inanimate object (and if so, whether the inanimate object isa device case and optionally the type of device case) or an animateobject that is subject to regulatory limits on SAR/MPE.

Control circuitry 14 may perform animate object detection based on anydesired metric for the variation of VSWR (e.g., |S₁₁|) measurements overtime. For example, control circuitry 14 may perform animate objectdetection based on the difference between the maximum |S₁₁| value andthe minimum Bill value measured at each of the sampling times. Forpoints 116, control circuitry 14 may identify (e.g., compute, calculate,generate, determine, etc.) a difference value Δ that is equal to thedifference between the maximum |S₁₁| value |S₁₁|MAX of points 116 (e.g.,as measured at time T1) and the minimum |S₁₁| value |S₁₁|MIN of points116 (e.g., as measured at time T2). For points 112, this differencevalue is relatively small (or zero in scenarios where each point 112 isat the same IS ill). Control circuitry 14 may compare difference value Δto one or more threshold values to determine whether the external objectis animate or animate (e.g., if difference value Δ exceeds the thresholdvalue, control circuitry 14 may determine that the external object isanimate). This example is merely illustrative and, in general, controlcircuitry 14 may identify any desired metric of variance in |S₁₁| forcomparison to one or more threshold values in determining whether theexternal object is animate or inanimate. As another example, controlcircuitry 14 may identify the mean and variance of the Bill measurementsover time, the rate of change of |S₁₁| measurements over time, and/orany other desired variation metrics for comparison to one or morethreshold values for determining whether the external object is animateor inanimate.

The example of FIG. 5 is merely illustrative. Points 114, 116, and 112may have other values in practice. In the example of FIG. 5 , fivesampling times T0-T4 are used to identify variations in |S₁₁| forperforming animate object detection. This is merely illustrative and, ingeneral, any desired number n of sampling times may be used to identifyvariations in |S₁₁| for performing animate object detection. Eachsampling time may be separated by 10 ms, 20 ms, 1-20 ms, more than 20ms, 10-50 ms, or any other desired period. The sampling times need notbe evenly spaced.

FIG. 6 is a plot of return loss (e.g., |S₄₄|) as a function of frequencyillustrating the effects of different removable cases on VSWRmeasurements by VSWR sensor 32. Curve 122 plots |S₄₄| in the absence ofa removable case and any other external object. Curve 118 plots |S₄₄| inthe presence of a first type of removable case (e.g., a removable casemade from a first material, having a first thickness, etc.). Curve 120plots |S₄₄| in the presence of a second type of removable case (e.g., aremovable case made from a second material, having a second thickness,etc.).

As shown by curves 122, 120, and 118, the presence of a removable casecauses a shift in the magnitude of the VSWR measurements made by VSWRsensor 32 (also shown by the difference between points 112 and points114 of FIG. 5 ). As shown by curves 120 and 118, different types ofcases may have different effects on the VSWR measurements made by VSWRsensor 32. However the same variations in VSWR measurements are made inthe presence of either type of removable case or in the absence of anyexternal object as a function of time (e.g., as shown by points 114 or112 of FIG. 5 ). Control circuitry 14 may compare the VSWR measurementsto expected VSWR measurements associated with different removable casetypes (e.g., curves 118 and 120) to identify what type of removable caseis present on device 10 if desired. In other words, control circuitry 14may compare variations in the VSWR measurements over time to one or morethresholds for performing animate object detection and may furthercompare the magnitude of the VSWR measurements (or the magnitude of anaverage of the VSWR measurements) to one or more thresholds forperforming removable case detection and identification. The example ofFIG. 6 is merely illustrative. Curves 118-122 may have other shapes inpractice.

FIG. 7 is flow chart of illustrative operations involved in using VSWRsensor 32 to determine whether external objects adjacent to transmitantenna 40TX are animate or inanimate. At operation 124, a givensampling period in which VSWR sensor 32 performs VSWR measurements(samples) for performing animate object detection may begin. Thesampling period may begin periodically (e.g., at a predetermined time,between other scheduled communications or signal transmissions, etc.) ormay begin in response to a trigger condition. The sampling period maybegin, for example, once VSWR sensor 32 has already detected thatexternal object 46 has passed within threshold range R_(TH) of transmitantenna 40TX (e.g., once VSWR measurements such as |S₁₁| measurementsreach a predetermined threshold value).

As another example, the sampling period may begin once device 10 hasdetermined that gathered wireless performance metric data has fallenoutside of a predetermined range. In this example, wireless circuitry 24may gather wireless performance metric data associated with theradio-frequency performance of transmit antenna 40TX and/or receiveantenna 40RX. The wireless performance metric data may includesignal-to-noise ratio (SNR) data, receive signal strength indicator(RSSI) data, or any other desired performance metric data gatheredduring the transmission of radio-frequency signals 38, the transmissionof radio-frequency signals 42, the reception of radio-frequency signals38, and/or the reception of reflected signals 44 of FIG. 1 , forexample. Control circuitry 14 may compare the gathered wirelessperformance metric data with a predetermined range of wirelessperformance metric values associated with satisfactory radio-frequencyperformance and/or the operation of wireless circuitry 24 in the absenceof external objects within threshold range R_(TH) (e.g., a predeterminedrange of satisfactory RSSI values, SNR values, etc.). The predeterminedrange of wireless performance metric values may be characterized by anupper threshold limit or value and/or a lower threshold limit or value.

The wireless performance metric data may serve as a coarse indicator forwhether external object 46 is within threshold range R_(TH). Forexample, if external object 46 is within range R_(TH), external object46 may partially block or cover one or more antennas 40 (therebypreventing the antenna from properly receiving radio-frequency signals),may undesirably load or detune one or more antennas 40 in device 10,etc. When the gathered wireless performance metric data falls outside ofthe predetermined range, this may be indicative of the potentialpresence of external object 46 within threshold range R_(TH). However,when the gathered wireless performance metric data falls within thepredetermined range, this may indicate that it is very unlikely thatthere is an external object present within threshold range R_(TH) (e.g.,because wireless circuitry 24 is performing nominally as expected in theabsence of an external object within threshold range R_(TH)). If thegathered wireless performance metric data falls within the predeterminedrange (thereby indicating that there is no external object withinthreshold range R_(TH)), VSWR sensor 32 may gather background VSWRmeasurements for performing background cancellation if desired.

VSWR sensor 32 may make n VSWR measurements such as |S₁₁| measurements(sometimes referred to herein as samples) during any given samplingperiod. Each of the n VSWR measurements may occur at a correspondingsampling time within the sampling period (e.g., at times T0-T4 of FIG. 5). The sampling period may be any desired length (e.g., n may be anydesired integer such as 2, between 3-5, between 5-10, between 10-20,100, more than 100, more than 10, more than 20, more than 5, more than2, etc.).

At operation 126, wireless circuitry 24 (e.g., sequential signalgenerator 108 or LO 106 of FIG. 3 ) may transmit test signal sigtx overtransmit path 34. Test signal sigtx may be transmitted at a singlefrequency (e.g., a single tone), at multiple frequencies (e.g., as adual tone or multiple tones), or may be swept over a range offrequencies. Transmit antenna 40TX may transmit test signal sigtx. Ifdesired, transmit antenna 40TX may forego transmission of test signalsigtx (e.g., antenna switch 94 of FIG. 3 may be open).

At operation 128, VSWR sensor 32 may perform a VSWR measurement (e.g.,may gather an |S₁₁| value) from the transmitted test signal sigtx (ormultiple VSWR measurements in scenarios where test signal sigtx is sweptover a range of frequencies) and may store the VSWR measurement(s) forsubsequent processing (e.g., on memory 104 of FIG. 3 ). This measurementmay occur at a corresponding sampling time within the sampling period(e.g., one of times T0-T4 of FIG. 5 ). If the full sampling period hasnot yet elapsed (e.g., if fewer than n samples or iterations ofoperations 126-128 have taken place for the current sampling period),processing may loop back to operation 126 via path 130. Each iterationof operations 126-128 may take a corresponding duration or period toperform (e.g., 10 ms, 20 ms, 1-20 ms, more than 20 ms, etc.). Each VSWRmeasurement (e.g., each iteration of operation 128) may therefore beseparated in time, thereby allowing VSWR measurements to be made overtime (e.g., over the sampling period) for identifying variations in theVSWR measurements over time for subsequent processing.

If the sampling period has elapsed (e.g., once n samples or iterationsof operations 126-128 have taken place), processing may proceed fromoperation 128 to operation 134 via path 132. At operation 134, controlcircuitry 14 (e.g., comparator/logic 102 of FIG. 3 or other controlcircuitry separate from measurement circuitry 70 of FIG. 3 ) mayidentify an amount of variation over time in the VSWR measurementsgathered and stored during the sampling period. For example, controlcircuitry 14 may identify a variation metric such as difference value Δfor the VSWR measurements, which is equal to the difference between themaximum stored |S₁₁| value (e.g., |S₁₁|MAX of FIG. 5 ) and the minimumstored |S₁₁| value (e.g., |S₁₁|MIN of FIG. 5 ) from the sampling period.This is merely illustrative and, in general, control circuitry 14 mayidentify other variation metrics such as the mean and variance of thestored |S₁₁| values if desired.

At operation 136, control circuitry 14 may perform animate objectdetection based on the identified variation in the VSWR measurementsgathered and stored during the sampling period. For example, controlcircuitry 14 may compare the identified variation (e.g., differencevalue Δ) to one or more threshold values indicative of whether externalobject 46 is animate or inanimate. The animate object detection mayallow control circuitry 14 to distinguish between external objects 46that are inanimate, such as a tabletop or removable case, from externalobjects 46 that are animate, such as a body part of the user of device10 or other persons.

If desired, control circuitry 14 may process the VSWR measurementsgathered and stored during the sampling period to identify whether aremovable case is present on device 10 and to optionally identify whattype of removable case is present on device 10 (at operation 138). Thesecase detection operations may be performed in response to identifyingthat external object 46 is an inanimate object, for example.

If desired, control circuitry 14 may identify a range to external object46 based on the identified variation in the VSWR measurements gatheredand stored during the sampling period (at operation 140). Controlcircuitry 14 may, for example, compare the identified variation to oneor more threshold values indicative of the presence of external object46 at different ranges within threshold range R_(TH).

If desired, control circuitry 14 may reduce the transmit power level ofantenna 40TX, may reduce the maximum transmit power level of antenna40TX (e.g., the upper limit or cap on transmit power levels used byantenna 40TX), may switch a different transmit antenna into use, and/ormay disable transmit antenna 40TX in response to determining thatexternal object 46 is an animate object. This may ensure that animateexternal objects, which are possibly or even likely human body parts,are not exposed to excessive radio-frequency energy, thereby ensuringthat device 10 continues to satisfy any regulatory limits on SAR or MPE.

The example of FIG. 7 is merely illustrative. Operations 138, 140,and/or 142 may be omitted. Control circuitry 14 may perform any otherdesired operations in response to the detection of an animate externalobject or an inanimate external object adjacent transmit antenna 40TX.If desired, control circuitry 14 may increase the transmit power level,may increase the maximum transmit power level, and/or may switchtransmit antenna 40TX into use in response to determining that externalobject 46 is an inanimate object.

FIG. 8 is a flow chart of illustrative operations involved in performinganimate object detection. The operations of FIG. 8 may be performed bycontrol circuitry 14 (e.g., one or more processors separate from and/orincluding portions of measurement circuitry 70 of FIG. 3 ) in performingoperation 136 of FIG. 7 , for example.

At operation 144 of FIG. 8 , control circuitry 14 may compare theidentified variation in VSWR measurements for the sampling period to aminimum variation threshold value. For example, control circuitry 14 maycompare difference value Δ to the minimum variation threshold value. Ifthe identified variation (e.g., difference value Δ) exceeds the minimumvariation threshold value (e.g., if there is a sufficient amount ofvariation in |S₁₁| over the sampling period), processing may proceed tooperation 148 via path 146.

At operation 148, control circuitry 14 may identify that external object46 is an animate (non-static) external object (e.g., because therelatively high amount of variation in |S₁₁| values gathered over thesampling period is indicative of an external object that moves at leastslightly adjacent transmit antenna 40TX, which is characteristic of apossible human body part). If desired, control circuitry 14 may reducethe transmit power level of transmit antenna 40TX, may reduce themaximum transmit power level of transmit antenna 40TX, may disabletransmit antenna 40TX, may switch a different transmit antenna into use,and/or may perform any other desired processing in response todetermining that external object 46 is an animate object (e.g., softwareapplications running on device 10 may use the presence of an animateobject adjacent to the device as a control input, etc.). This may ensurethat device 10 continues to satisfy regulatory limits on SAR/MPE giventhe potential (or likely) presence of a body part near to transmitantenna 40TX.

At optional operation 150, control circuitry 14 may identify the rangeto external object 46 based on the identified variation in stored VSWRmeasurements. For example, the amount of variation in the stored VSWRmeasurements may be correlated to the range between the animate externalobject and transmit antenna 40TX. Control circuitry 14 may compare theidentified variation (e.g., difference value Δ) to one or moreadditional threshold values indicative of the animate external objectbeing located at different distances from transmit antenna 40TX toidentify the range between device 10 and the animate external object.Control circuitry 14 may use the identified range for any other desiredprocessing or application tasks. Optional operation 150 may be omittedif desired.

If the identified variation (e.g., difference value Δ) is less than theminimum variation threshold value (e.g., if there is an insufficientamount of variation in |S₁₁| over the sampling period), processing mayproceed from operation 144 to operation 154 via path 152. At operation154, control circuitry 14 may identify that external object 46 is aninanimate (static) external object (e.g., because the relatively lowamount of variation in |S₁₁| values gathered over the sampling period isindicative of an external object that does not move, unlike a human bodypart). If desired, control circuitry 14 may forego decreasing thetransmit power level or the maximum transmit power level of transmitantenna 40TX. In other words, control circuitry 14 may maintain thecurrent maximum transmit power level of transmit antenna 40TX or mayincrease the maximum transmit power level of transmit antenna 40TX. Ifdesired, control circuitry 14 may increase the transmit power level oftransmit antenna 40TX, may switch transmit antenna 40TX into use, and/ormay perform any other desired processing in response to determining thatexternal object 46 is an inanimate object (e.g., software applicationsrunning on device 10 may use the presence of an inanimate objectadjacent to the device as a control input, etc.). This may help tomaximize the radio-frequency performance of wireless circuitry 24 inperforming wireless communications and/or long range spatial rangingoperations (e.g., maximizing throughput, signal quality, signal-to-noiseratio, etc.) relative to scenarios where transmit power level or maximumtransmit power level is reduced for all external objects 46 withinthreshold range R_(TH) regardless of whether the external object isanimate or inanimate. Because the inanimate object is not a human bodypart, omitting a reduction in transmit power level or maximum transmitpower level will not cause device 10 to exceed regulatory limits onSAR/MPE.

If desired, control circuitry 14 may also perform case detection atoperation 154. For example, control circuitry 14 may compare one or moreof the stored VSWR measurements (or an average of the stored VSWRmeasurements) to one or more predetermined VSWR measurements (e.g.,|S₁₁| values) stored on device 10 to determine whether a removable caseis present on device 10. The predetermined VSWR measurements may be, forexample, expected VSWR measurements gathered for device 10 (e.g., duringfactory calibration) in the absence of any external objects or aremovable case (e.g., one or more of points 114 or an average of points114 of FIG. 5 ).

If the difference between the stored VSWR measurement(s) and thepredetermined VSWR measurement(s) is less than a threshold differencevalue (or if the stored VSWR measurements are otherwise sufficientlysimilar to the predetermined VSWR measurements), processing may proceedto operation 158 via path 156. At operation 158, control circuitry 14may identify that the inanimate external object is not a removable caseor is not present adjacent transmit antenna 40TX. However, if thedifference between the stored VSWR measurement(s) and the predeterminedVSWR measurement(s) exceeds the threshold difference value (or if thestored VSWR measurements are sufficiently dissimilar to thepredetermined VSWR measurements), processing may proceed to optionaloperation 162 via path 160.

At optional operation 162, control circuitry 14 may identify a type ofremovable case present on device 10. For example, control circuitry 14may compare one or more of the stored VSWR measurements (e.g., anaverage of the stored VSWR measurements, the VSWR measurements as afunction of frequency) to one or more predetermined VSWR measurementsstored on device 10 to determine the type of removable case present.These predetermined VSWR measurements may be, for example, expected VSWRmeasurements gathered for device 10 (e.g., during factory calibration)while placed into a variety of different removable case types. As anexample, control circuitry 14 may compare the stored VSWR measurementsto curves such as curves 118 and 120 of FIG. 6 to determine whether theremovable cases associated with curves 118 or 120 are present on device10. If desired, operation 162 may be combined with operation 154 (e.g.,control circuitry 14 may compare the stored VSWR measurements to thepredetermined VSWR measurements associated with different types ofremovable cases and, if the VSWR measurements are not sufficientlysimilar to any of the predetermined VSWR measurements, processing mayproceed from operation 154 to operation 158). Operation 162 may beomitted if desired.

At operation 164, control circuitry 14 may identify that the inanimateexternal object is a removable device case (and optionally the type ofremovable device case). Control circuitry 14 may perform additionalprocessing based on the detected presence of the removable device caseand/or the identified type of case. For example, control circuitry 14may use VSWR sensor 32 to gather background VSWR measurements in theabsence of other external objects within threshold range R_(TH), wherethe background VSWR measurements take into account the presence of theremovable device case. Control circuitry 14 may then use the backgroundVSWR measurements to perform background cancellation on subsequent VSWRmeasurements that are gathered in the presence of another externalobject within threshold range R_(TH) while device 10 is placed withinthe removable case (e.g., by subtracting the background VSWRmeasurements from the subsequent VSWR measurements). In other words,VSWR detector 32 may perform VSWR background cancellation based on thedetected presence of the removable device case on device 10. As anotherexample, control circuitry 14 may control the impedance matching and/orantenna tuning of transmit antenna 40TX based on the presence of theremovable device case and optionally the type of removable device case(e.g., to compensate for impedance loading or detuning of the antenna onaccount of the presence of the removable device case). As yet anotherexample, control circuitry 14 may use the presence of the removable caseand optionally the type of removable case to calibrate long rangespatial ranging operations performed using transmit antenna 40TX (e.g.,to compensate for path delay effects of the transmitted and/or reflectedsignals passing through the removable case).

Curve 168 of FIG. 9 shows one example of how variation in |S₁₁| may becorrelated with the range between the external object and transmitantenna 40TX. If desired, control circuitry 14 may compare theidentified variation in the stored VSWR measurements to curve 168 toidentify the corresponding range between the external object andtransmit antenna 40TX (e.g., while processing operation 150 of FIG. 8 ).Curve 168 may be stored on device 10 (e.g., during factory calibration,manufacture, assembly, testing, etc.). The example of FIG. 9 is merelyillustrative and, in practice, curve 168 may have other shapes.

FIG. 10 shows two exemplary timing diagrams for performing VSWRmeasurements for use in performing animate object detection. Timingdiagram 170 illustrates one arrangement in which VSWR measurements forperforming animate object detection are time-interleaved(time-multiplexed) with other transmit operations. During samplingperiods 172, control circuitry 14 may perform n iterations of operations126 and 128 of FIG. 7 . The n VSWR measurements during each samplingperiod 172 may be processed to identify a corresponding variation andthe variation may be processed to determine whether external object 46is animate or inanimate (e.g., while processing operations 134-136).During periods 174, transmit antenna 40TX may be used to transmit othersignals such as radar signals for performing long term spatial rangingor wireless communications signals. Operations 134-136 of FIG. 7 may beperformed during each sampling period 172 or may, if desired, extendinto the subsequent period 174.

Timing diagram 176 illustrates another arrangement in which VSWRmeasurements for performing animate object detection are performedduring rolling sampling periods 172. As shown by timing diagram 176,each sampling period for identifying variation in VSWR measurements mayinclude a subset of the samples from the previous sampling period aswell as additional samples after the previous sampling period haselapsed. This may allow wireless circuitry 24 to continuously determinewhether external object 46 is animate or inanimate, for example. Theexamples of FIG. 10 are merely illustrative. The timing arrangements oftiming diagrams 170 and 176 may be combined if desired. The signalstransmitted during periods 174 may be used as test signal sigtx ifdesired (e.g., separate sampling periods 172 may be omitted). Othertiming arrangements for sampling period 172 may be used if desired.

The methods and operations described above in connection with FIGS. 1-10may be performed by the components of device 10 using software,firmware, and/or hardware (e.g., dedicated circuitry or hardware).Software code for performing these operations may be stored onnon-transitory computer readable storage media (e.g., tangible computerreadable storage media) stored on one or more of the components ofdevice 10 (e.g., storage circuitry 16 of FIG. 1 ). The software code maysometimes be referred to as software, data, instructions, programinstructions, or code. The non-transitory computer readable storagemedia may include drives, non-volatile memory such as non-volatilerandom-access memory (NVRAM), removable flash drives or other removablemedia, other types of random-access memory, etc. Software stored on thenon-transitory computer readable storage media may be executed byprocessing circuitry on one or more of the components of device 10(e.g., processing circuitry 18 of FIG. 1 , etc.). The processingcircuitry may include microprocessors, central processing units (CPUs),application-specific integrated circuits with processing circuitry, orother processing circuitry. The components of FIGS. 1 and 3 may beimplemented using hardware (e.g., circuit components, digital logicgates, etc.) and/or using software where applicable.

The foregoing is merely illustrative and various modifications can bemade to the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. An electronic device operable in an environmentthat includes an external object, the electronic device comprising: anantenna; a transmitter coupled to the antenna over a radio-frequencytransmission line path, the transmitter being configured to transmitradio-frequency signals to another electronic device using the antennaand the radio-frequency transmission line path; a voltage standing waveratio (VSWR) sensor disposed on the radio-frequency transmission linepath, the VSWR sensor being configured to perform VSWR measurementsusing the radio-frequency signals transmitted by the transmitter; radarcircuitry communicably coupled to the antenna and configured to detect arange to the external object based on a radar signal transmitted by theantenna and received by the radar circuitry; and one or more processorsconfigured to calibrate the detected range to compensate for a path lossassociated with a removable case detected based on the VSWRmeasurements.
 2. The electronic device of claim 1, wherein the one ormore processors being further configured to reduce a maximum transmitpower level of the antenna based on the VSWR measurements.
 3. Theelectronic device of claim 2, the one or more processors being furtherconfigured to increase the maximum transmit power level of the antennabased on the VSWR measurements.
 4. The electronic device of claim 1, theone or more processors being further configured to detect the removablecase based on a magnitude of the VSWR measurements.
 5. The electronicdevice of claim 4, wherein the VSWR sensor is configured to perform abackground VSWR measurement in response to the one or more processorsdetermining that the external object is the removable case, the one ormore processors being further configured to background-cancel subsequentVSWR measurements by the VSWR sensor based on the background VSWRmeasurement.
 6. The electronic device of claim 1, the one or moreprocessors being further configured to identify a range between theexternal object and the antenna based on a variation in the VSWRmeasurements.
 7. The electronic device of claim 1, wherein the radarcircuitry comprises a sequential signal generator and the sequentialsignal generator is configured to generate the radar signal.
 8. Theelectronic device of claim 1, the one or more processors being furtherconfigured to: compare a variation in the VSWR measurements to athreshold value; determine that the external object is animate when theidentified variation in the VSWR measurements exceeds the thresholdvalue; and determine that the external object is inanimate when theidentified variation in the VSWR measurements is less than the thresholdvalue.
 9. A method of operating an electronic device, the methodcomprising: with a signal generator, transmitting radio-frequencysignals during a sampling period over a radio-frequency transmissionline communicably coupled to an antenna; with a voltage standing waveratio (VSWR) sensor disposed along the radio-frequency transmissionline, performing VSWR measurements from the radio-frequency signalstransmitted over the radio-frequency transmission line during thesampling period; with one or more processors, detecting a removable caseon the electronic device based on the VSWR measurements; with radarcircuitry, transmitting and receiving a radar signal using the antenna;with one or more processors, detecting a range to an external objectbased on the transmitted and received radar signal; and with the one ormore processors, calibrating the detected range to compensate for a pathloss associated with the removable case detected based on the VSWRmeasurements.
 10. The method of claim 9, wherein performing the VSWRmeasurements comprises performing at least two VSWR measurements thatare separated by at least 10 ms.
 11. The method of claim 9, wherein thesampling period comprises a rolling sampling period.
 12. An electronicdevice comprising: an antenna; a transmitter coupled to the antenna overa radio-frequency transmission line path, the transmitter beingconfigured to transmit radio-frequency signals using the antenna and theradio-frequency transmission line path; a voltage standing wave ratio(VSWR) sensor disposed on the radio-frequency transmission line path,the VSWR sensor being configured to gather VSWR values from theradio-frequency signals transmitted by the antenna; and one or moreprocessors configured to detect a range to an external object based onthe radio-frequency signals transmitted by the antenna and a reflectedversion of the radio-frequency signals transmitted by the antenna, andcalibrate the detected range based on a removable case detected, by theone or more processors, based on the VSWR values.
 13. The electronicdevice of claim 12, the one or more processors being further configuredto perform removable case detection when a variation in the VSWR valuesis less than a threshold value.
 14. The electronic device of claim 13,wherein the VSWR values are gathered over a sampling period, the one ormore processors being further configured to identify the variation inthe VSWR values by subtracting a minimum of the VSWR values gatheredover the sampling period from a maximum of the VSWR values gathered overthe sampling period.